1. Field of the Invention
The present invention relates to a grid sheath for a medical instrument that is used to assist in implanting seeds, such as radioactive seeds, into a patient""s body. In particular, the present invention relates to a grid sheath used to couple to a medical instrument that implants radioactive seeds into a patient""s prostate gland, for example, in order to treat prostate cancer.
2. Description of the Related Art
For treating prostate cancer, radioactive seeds are provided to various locations within a patient""s prostate gland, by way of a medical instrument, also called a seed implantation device. Typically, a base unit which includes an ultrasound unit is used to determine the exact location of the patient""s prostate gland with respect to the base unit. FIG. 9 shows a base unit 912 with a grid template 170 mounted to it. The ultrasound unit of the base unlit 912 includes a probe 915, which is inserted into the patient""s rectum while the patient is lying on his back. The grid template 170 is mounted onto the base unit via extendible rods 914, whereby the grid template includes a plurality of rows and columns of holes in which a needle can be inserted. Typically, the grid template includes 13 by 13 matrix of needle holes, where adjacent holes on a row or column are 5 mm apart. Every other row is labeled with a number, and every other column is labeled with an alphabetic character. There is a direct relation between the center line axis of the ultrasound probe and the position of the holes of the grid template. The base unit 912 is capable of moving either inwards or outwards with respect to the patient.
A needle is provided through a hole on the grid template, and then inserted into a region within the patient""s body in which the prostate gland is located. By using the ultrasound unit, a precise position of the proximal and distal positions of the prostate gland can be determined and recorded. The distal position of the prostate gland is also called the xe2x80x9czero retraction planexe2x80x9d. Once that information is recorded, a pre-plan can be determined by a doctor, where the pre-plan corresponds to a plan for injecting seeds into particular locations within the patient""s prostate gland. Such treatment is generally started by placing the needle at the zero retraction point, and then applying seeds with respect to that reference point.
For a conventional seed implantation device, a needle is first placed into a particular hole of the grid template, and then the seed implantation device is held in place by a doctor and attached to the needle. The seed implantation device is then used to inject one or more seeds into the patient""s body through the needle. When finished with that hole, the seed implantation device is deattached from the needle, and placed aside. Then, the needle is removed from the grid template, and a new needle is positioned at another hole of the grid template, according to the specific pre-plan for treating the patient""s prostate gland. Alternatively, all the needles can be placed in holes of the grid template in advance. One such conventional seed implantation device is called a MICK applicator, and requires the operator to physically reposition the MICK applicator proximally in order to place subsequent seeds.
With these conventional devices, there is no way to automatically move the instrument back while it is attached to a needle on the grid template.
The present invention provides a grid sheath for a seed implantation device that is used to provide seeds to the patient via a needle coupled to a front portion of the seed implantation device, so as allow a doctor to easily hold a medical instrument in its proper place while performing the seed implantation. The grid sheath adapts to the seed implantation device to allow automatic advancement of the needle relative to the grid template.
According to one aspect of the invention, there is provided a grid sheath for a medical instrument. The grid sheath includes a sheath unit configured to couple to the medical instrument, and to allow the medical instrument to move relative to the sheath unit. The grid sheath also includes at least one plate support rod that is coupled to a distal end of the sheath unit. The grid sheath further includes a push plate that is coupled to a distal end of the at least one plate support rod. The push plate is configured to abut against a girid template to allow an operator to manually operate the medical instrument while maintaining the medical instrument in a particular x, y location with respect to the grid template.
According to another aspect of the invention, there is provided a grid sheath for a medical instrument. The grid sheath includes a sheath unit configured to couple to the medical instrument, and to allow the medical instrument to move relative to the sheath unit. The grid sheath also includes at least one plate support rod that is coupled to a distal end of the sheath unit. The grid sheath further includes a push plate that is coupled to a distal end of the at least one plate support rod. The medical instrument has a needle nozzle that allows for a needle to be engaged with the medical instrument. The at least one plate support rod is of a size such that the push plate is not in contact with the grid template when the needle is engaged with the medical instrument. Either the plate support rod is capable of being lengthened to make the push plate be in contact with a surface of the grid template, or the medical instrument is capable of moving an amount relative to the sheath unit so that the push plate is put in contact with the surface of the grid template.